The fibroblast growth factor family (FGF) of neurotrophic and mitogenic factors has been implicated in ocular development and disease. These factors can act as mitogens for retinal progenitor cells, induce neovascularization, and effect the state of differentiation of the pigmented epithelium. Expression of the messenger RNA encoding these factors and cognate receptors has been demonstrated for several periods during development and in the adult eye. This proposal aims to further define the role(s) of these factors in vivo in eye development; to determine whether they can induce neovascularization when overexpressed; to determine if reduction in expression can block neovascularization; and to determine whether they play a role in postnatal eye growth. FGF genes and the FGF receptor genes will be introduced into developing eyes of rodents and chicks using retrovirus vectors. This has been previously been demonstrated to be a successful way to achieve stable gene expression in ocular tissue in vivo. The various assays and protocols explore different ways to effect levels of expression of the FGF family. If controlling expression levels using gene transfer can be achieved, there is a potential for using this strategy, or a derivative of it, for control of neovascularization in e.g. diabetic retinopathy.